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I've seen a number of questions asking similar questions to the above, but I couldn't see that anyone had asked my specific question yet, so here goes.

I'm about to buy a Gigabyte GV-R725O5-2GI PCIe 3.0 x8 video card.

My motherboard has PCIe 2.0 x16 slots.

My question is whether the card will run in PCIe 2.0 x16 or PCIe 2.0 x8.

Obviously, the number of lanes on the card is a physical issue (i.e. how many wires it has). So presumably, if it is PCIe 3.0 x8 it only has 8 lines, so will run PCIe 2.0 x8 on my motherboard. Is that right?